I really hate it when I approach a set of doors and the one I happen to try to use is locked, where some arbitrary other ones are unlocked. I hate it for a few reasons:
1) I feel like an idiot and look like an idiot, pushing into a door, expecting it to move and it not moving. This is exacerbated by others with me going through nearby doors with no problem.
2) I think of all the time wasted by all the people all day trying to get through the door and failing, just because some jackass custodian was lazy and didn't want to take the extra twenty seconds in the morning to unlock all the doors.
At Georgia Tech I actually used to call in complaints about this when I discovered it in my building. It never got better. So much for local activism.
Once I was in a foul mood and I encountered this. I bitched about it to someone and he said "You shouldn't let the little things get to you, man." He was right, of course.